Different methods for removing boron-rich layer and their impacts on the efficiency of interdigitated back contact solar cells

In this paper, three commonly used methods for boron-rich layer (BRL) (BRL: abbreviation of boron-rich layer, a layer constituted by compound of boron and silicon.) removal and their impacts on the surface passivation and the efficiency of the final interdigitated back contact solar cells are investigated. The method of in-situ oxidation can remove BRL completely, but will cause serious degradation of the bulk lifetime. The method of treatment in boil nitric acid cannot remove BRL completely resulting in a poor passivation quality of the substrate surface. The method of chemical etch treatment (CET) (CET: Abbreviation of chemical etch treatment.) can remove BRL completely and would not cause any degradation of the bulk lifetime. Finally, interdigitated back contact solar cells have been fabricated using the three methods mentioned above for BRL removal and the highest efficiency of 21.17% is achieved with the BRL removed by the method of CET.